// Copyright 2016 the V8 project authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

#include "src/builtins/builtins-utils-inl.h"
#include "src/builtins/builtins.h"
#include "src/conversions.h"
#include "src/counters.h"
#include "src/heap/factory.h"
#include "src/isolate.h"
#include "src/objects-inl.h"
#include "src/objects/js-array-buffer-inl.h"

namespace v8 {
namespace internal {

    // -----------------------------------------------------------------------------
    // ES #sec-dataview-objects

    // ES #sec-dataview-constructor
    BUILTIN(DataViewConstructor)
    {
        HandleScope scope(isolate);
        if (args.new_target()->IsUndefined(isolate)) { // [[Call]]
            THROW_NEW_ERROR_RETURN_FAILURE(
                isolate, NewTypeError(MessageTemplate::kConstructorNotFunction, isolate->factory()->NewStringFromAsciiChecked("DataView")));
        }
        // [[Construct]]
        Handle<JSFunction> target = args.target();
        Handle<JSReceiver> new_target = Handle<JSReceiver>::cast(args.new_target());
        Handle<Object> buffer = args.atOrUndefined(isolate, 1);
        Handle<Object> byte_offset = args.atOrUndefined(isolate, 2);
        Handle<Object> byte_length = args.atOrUndefined(isolate, 3);

        // 2. If Type(buffer) is not Object, throw a TypeError exception.
        // 3. If buffer does not have an [[ArrayBufferData]] internal slot, throw a
        //    TypeError exception.
        if (!buffer->IsJSArrayBuffer()) {
            THROW_NEW_ERROR_RETURN_FAILURE(
                isolate, NewTypeError(MessageTemplate::kDataViewNotArrayBuffer));
        }
        Handle<JSArrayBuffer> array_buffer = Handle<JSArrayBuffer>::cast(buffer);

        // 4. Let offset be ? ToIndex(byteOffset).
        ASSIGN_RETURN_FAILURE_ON_EXCEPTION(
            isolate, byte_offset,
            Object::ToIndex(isolate, byte_offset, MessageTemplate::kInvalidOffset));
        size_t view_byte_offset = byte_offset->Number();

        // 5. If IsDetachedBuffer(buffer) is true, throw a TypeError exception.
        //    We currently violate the specification at this point. TODO: Fix that.

        // 6. Let bufferByteLength be the value of buffer's
        // [[ArrayBufferByteLength]] internal slot.
        size_t const buffer_byte_length = array_buffer->byte_length();

        // 7. If offset > bufferByteLength, throw a RangeError exception.
        if (view_byte_offset > buffer_byte_length) {
            THROW_NEW_ERROR_RETURN_FAILURE(
                isolate, NewRangeError(MessageTemplate::kInvalidOffset, byte_offset));
        }

        size_t view_byte_length;
        if (byte_length->IsUndefined(isolate)) {
            // 8. If byteLength is either not present or undefined, then
            //       a. Let viewByteLength be bufferByteLength - offset.
            view_byte_length = buffer_byte_length - view_byte_offset;
        } else {
            // 9. Else,
            //       a. Let viewByteLength be ? ToIndex(byteLength).
            //       b. If offset+viewByteLength > bufferByteLength, throw a
            //          RangeError exception.
            ASSIGN_RETURN_FAILURE_ON_EXCEPTION(
                isolate, byte_length,
                Object::ToIndex(isolate, byte_length,
                    MessageTemplate::kInvalidDataViewLength));
            if (view_byte_offset + byte_length->Number() > buffer_byte_length) {
                THROW_NEW_ERROR_RETURN_FAILURE(
                    isolate, NewRangeError(MessageTemplate::kInvalidDataViewLength));
            }
            view_byte_length = byte_length->Number();
        }

        // 10. Let O be ? OrdinaryCreateFromConstructor(NewTarget,
        //     "%DataViewPrototype%", «[[DataView]], [[ViewedArrayBuffer]],
        //     [[ByteLength]], [[ByteOffset]]»).
        Handle<JSObject> result;
        ASSIGN_RETURN_FAILURE_ON_EXCEPTION(
            isolate, result,
            JSObject::New(target, new_target, Handle<AllocationSite>::null()));
        for (int i = 0; i < ArrayBufferView::kEmbedderFieldCount; ++i) {
            Handle<JSDataView>::cast(result)->SetEmbedderField(i, Smi::kZero);
        }

        // 11. Set O's [[ViewedArrayBuffer]] internal slot to buffer.
        Handle<JSDataView>::cast(result)->set_buffer(*array_buffer);

        // 12. Set O's [[ByteLength]] internal slot to viewByteLength.
        Handle<JSDataView>::cast(result)->set_byte_length(view_byte_length);

        // 13. Set O's [[ByteOffset]] internal slot to offset.
        Handle<JSDataView>::cast(result)->set_byte_offset(view_byte_offset);

        // 14. Return O.
        return *result;
    }

} // namespace internal
} // namespace v8
